The invention relates to nuclear magnetic resonance (NMR) spectroscopy, and in particular to systems and methods for forming demountable cryogenic NMR connections in NMR spectrometers.
Nuclear magnetic resonance (NMR) spectrometers typically include a superconducting magnet for generating a static magnetic field B0, and an NMR probe including one or more special-purpose radio-frequency (RF) coils for generating a time-varying magnetic field B1 perpendicular to the field B0, and for detecting the response of a sample to the applied magnetic fields. Each RF coil and associated circuitry can resonate at the Larmor frequency of a nucleus of interest present in the sample. The direction of the static magnetic field B0 is commonly denoted as the z-axis or longitudinal direction, while the plane perpendicular to the z-axis is commonly termed the x-y or transverse direction. The RF coils are typically provided as part of an NMR probe, and are used to analyze samples situated in sample tubes or flow cells.
The design of NMR probes is commonly subject to design constraints specific to NMR systems. In particular, the design of NMR probes is commonly subject to tight spatial constraints. Moreover, NMR probes include highly-sensitive RF circuits which are subject to interference from various components of the probes.
Cryogenically cooled probes often allow achieving better sensitivity than conventional room-temperature probes. The increase in sensitivity of cryogenically cooled probes allows effective data acquisition from limited sample sizes and concentrations. At the same time, cryogenic probes introduce new challenges to NMR system designers. For example, system designers may need to establish durable, good-conductivity, NMR-compatible thermal and electrical connections between various NMR probe components at low temperatures.
In a common approach, soldering is used to establish various thermal and/or electrical connections between NMR probe components. For example, NMR measurement circuit components such as capacitors, inductors, or NMR RF coil(s) may be soldered to one or more cryogenically-cooled NMR probe boards (e.g. the probe cold head). Soldering creates a permanent connection, and exposure to heat during the soldering process can adversely affect some system components. At the same time, soldering has remained a common connection method because of the relative difficulty of establishing durable, stable, NMR-compatible connections having good thermal and/or electrical conduction properties between cryogenically-cooled components.